I have personally been using Windows 7 for many months as I was running the pre-release Beta version. It is a big improvement over Windows Vista. Performance all round is improved.
It may not be the cheapest upgrade but its well worth the expense if better performance is your aim.
You will need a minimum of 1 Gb of memory to run Windows 7 at its best. If you have any queries don't hesitate to email or phone me.